How to use Windows Live Writer behind proxy?

I was attempted to set up Windows Live Writer for a friend recently, however he is behind a proxy using Windows authentication, therefore, we were able to run the downloader, Windows Live Writer was unable to connect to the blog and was therefore, we had this error message while trying to set up the blog service:

Error 407: Proxy Authentication Required

Fortunately, Windows Live Writer was developed within the .NET framework and the walk-around is fairly easy.

First, open up the directory where the Windows Live Installer was installed at, which, in my case, is C:\Program Files (x86)\Windows Live\Writer

If you are not sure about that, right-click and select Properties, that will give you the folder path where Windows Live Writer was installed to:

In that folder, look a file named WindowsLiveWriter.exe.config:

Right click and open the file in notepad and this should be what you see initially:

Now add the following lines right after the <configuration> tag:

If you are using Windows-integrated authentication, this is what you should add:

Save it and restart Windows Live Writer and time to enjoy the power of Windows Live Writer:

The matter is a bit more complicated when you are using your own proxy address which is not default or you have your own proxy credentials which is not integrated with Windows. There is a solution here which I have not tried and therefore can not verify it. Basically you will need to compile your own DLL and add that to the configurations.